Neural interfaces technology is a rapidly growing segment of the medical device market. This technology mainly refers to devices that serve as an inter-connect between the stimulation/recording systems and the neuro-muscular tissue in the body. There currently are several known neuro-stimulation systems. Some notable neuro-stimulation systems include the cardiac pacemaker, cochlear implants, deep brain stimulation systems, spinal cord stimulation systems, gastric stimulation systems, vagal nerve stimulation systems, phrenic nerve stimulation systems, and others. Most of these systems include devices that are completely implantable into the human body, such as a patient.
Although not as prevalent as the neuro-stimulation systems, there are many non-implantable recording systems that can be used to record muscle and neural activity to control prostheses. There are also experimental systems being developed for implantable muscle and neural recordings.
In most of the neuro-stimulation/recording systems, it is common practice to test and calibrate the implanted electrodes, i.e., electrodes that are implanted into the body of the patient, prior to implanting the entire stimulator unit and/or recording unit into the patient's body. Specifically, the desired electrodes are first implanted at the target location in the patient's body and their efficacy is tested over a period of multiple days by using an external stimulator/recorder. After the trial period is over, if the electrodes function as intended, then the external connector is disconnected, and the leads are connected to an implantable stimulator/recorder that is programmed appropriately. On the other hand, if the electrodes do not function as intended, then only the electrodes need to be removed from the body instead of the whole implant. During the trial period, the leads from the implanted electrodes are connected to an external connector assembly through a percutaneous lead system. The stimulation/recording system plugs into the external connector assembly. In addition to being used during the trial period, the external connector assembly-percutaneous lead system can also be used to test novel electrode technology. This in particular usually requires the connector system to be functional for extended periods, such as from six months to one year.
Unfortunately, most known commercial percutaneous systems in the market today suffer from one or more of the following limitations:                a) they are often designed and used for a limited period, such as a trial period lasting over from two to seven days;        b) they often have high failure rates due to connector wear and tear, which is problematic because the electrodes will have to be replaced if the connector fails;        c) they often have high profile heights, particularly such systems that are designed for use as cranial implants; and/or        d) they are often not easily expandable.        
Although multiple versions of inline connector and percutaneous systems have been developed and patented previously, none of them have a complete modular structure as the one presented in this document.
Hence a need exists to develop a modular, convenient and reliable connector system to link the stimulation/recording system (external non-implanted or internal implanted) to implanted electrodes. In one or more preferred forms, it would also be preferable that the connector system satisfy any one or more of the following conditions:                a) it may be designed to minimize trauma to the patient both from the surgical installation procedure and also from the day-to-day use;        b) all or at some parts of the connector system (external, internal and percutaneous section) may be designed so as to minimize the possibility of infection;        c) parts subject to wear and tear may be designed to be easily replaceable without need for surgical intervention;        d) external components may be designed to have a low profile height and should also occupy minimal footprint on the skin to minimize skin abrasions;        e) it may be designed to be easily expandable to accommodate additional electrodes; and/or        f) it may be designed to be modular to allow electrodes to be connected to either an external or an internal stimulation/recording system.        